1. Field of the Invention
This invention relates to markers for lines, such as electric wire or other types having a uniform diameter, where the use, e.g., electric wire to confine, involves spans between attachment locations with a resultant need to warn of the existence of the line.
2. Prior Art
It has been recognized for some time that line spanning points of attachment, such as electric wire between fence posts, can be difficult to see and presents a possible safety problem. Other lines spanning points of attachment that can present a safety problem include rope securing corners or edges of a tent to a ground stake and line anchoring an airplane. Such lines may be a hazard to animals as well as humans. In general, any line across an open space presents a hazard.
Line markers that rely on elements of the line being marked to retain them in place are not useful on smooth line or line having a uniform diameter.
An example of a marker that relies on elements of the line being marked for holding the marker in place is disclosed in U.S. Pat. No. 297,487 granted C. H. Bacon on Apr. 22, 1884. However, the device disclosed in the Bacon patent is not useful on line, such as electric fence wire, because there is nothing to keep it in place on a smooth wire, i.e., wire that has an essentially uniform diameter throughout its length. It is stated in column 3 at lines 28 to 35 of the Bacon patent that "If some provision or means were not present on the wire to limit the longitudinal movement of the visible guards and signals, the same would be liable to nest or collect at one or the other ends of the wire adjacent to the posts owing to the motion of the wind or to caprices of individuals." The means present on the wire in the Bacon patent are the barbs of the barbed wire [Col. 3, line 26-28 of Bacon]. There is nothing integral or that is part of the guide or marker that keeps the marker in place on the wire.
Approaches to mark line, such as electric fence line, have not been satisfactory because of difficulty in keeping the marker in place on the line.
In the past, line has been marked by cloth strips or some other material tied to the line at selected intervals in the open space. The problem with this approach is that the cloth or other material does not stay in place and typically has a short life. Cloth, especially, deteriorates when exposed to the elements, such as wind, rain, freezing temperatures or excessively high temperatures.
Another approach is drilling through a ball, like a hollow, plastic ball or ping-pong ball, and threading the line through the holes. This approach is cumbersome and work intensive. Additionally, it is difficult to get the ball to stay in the desired location.